Process and apparatus for improving the removal of harmful components from engine exhaust gases

ABSTRACT

In the operation of an internal combustion engine, the catalyst bed of a catalytic muffler can be brought more rapidly to its effective operating temperature during the warmup period by combining, just after the engine start-up, the exhaust gases with air and unburned fuel, igniting the mixture and passing the hot combustion products in direct heat exchange with the cold catalyst bed. The process is interrupted when a period of time has elapsed so that a portion of the catalyst bed has been elevated to a temperature sufficiently high so as to be effective. A catalytic muffler equipped with an interconnected combustion chamber and catalyst-containing chamber may be used for the above purpose. The combustion chamber is provided with an inlet for a mixture of air, supplied by a blower, and exhaust gases, means for injecting unburned fuel as a spray, and means for igniting the combination of air, exhaust gases and unburned fuel. Suitable timing means are provided for initiating and terminating the operation of the blower, injection means and ignition means.

United States Patent [191 Pollock PROCESS AND APPARATUS FOR IMPROVINGTHE REMOVAL OF COMPONENTS FROM ENGINE EXHAUST GASES [75] Inventor:

[73] Assignee: Phillips Petroleum Company,

Bartlesville, Okla.

22 Filed: Sept. 27, 1971 21 Appl. No.: 183,886

[51] Int. Cl. F021) 75/10 [58] Field of Search 60/303, 284, 286, 60/300[56] References Cited UNITED STATES PATENTS 2,806,346 9/1957 Clayton60/284 3,020,903 2/1962 Kloss 2,937,490 5/1960 Calvert 3,226,206 12/1965I-lettick 3,254,483 6/1966 Martin 3,273,971 9/1966 Baddorf 60/284FOREIGN PATENTS OR APPLICATIONS 1,308,736 10/1962 France 60/284 Lyle W.Pollock, Bartlesville, Okla.

[ Aug. M, 1197.3

Primary Examiner-Douglas Hart Attorney-Young and Quigg [5 7] ABSTRACT Inthe operation of an internal combustion engine, the catalyst bed of acatalytic muffler can be brought more rapidly to its effective operatingtemperature during the warmup period by combining, just after the enginestart-up, the exhaust gases with air and unburned fuel, igniting themixture and passing the hot combustion products in direct heat exchangewith the cold catalyst bed. The process is interrupted when a period oftime has elapsed so that a portion of the catalyst bed has been elevatedto a temperature sufficiently high so as to be effective.

A catalytic muffler equipped with an interconnected combustion chamberand catalyst-containing chamber may be used for the above purpose. Thecombustion chamber is provided with an inlet for a mixture of air,supplied by a blower, and exhaust gases, means for injecting unburnedfuel as a spray, and means for igniting the combination of air, exhaustgases and unburned fuel. Suitable timing means are provided forinitiating and terminating the operation of the blower, injection meansand ignition means.

5 Claims, 2 Drawing Figures PROCESS AND APPARATUS FOR IMPROVING THEREMOVAL OF HARMFUL COMPONENTS FROM ENGINE EXHAUST GASES BACKGROUND OFTHE INVENTION This invention relates to a process and apparatus for theremoval of harmful substances from the exhaust gases of internalcombustion engines. In another as pect, it relates to a process andapparatus for catalytically oxidizing to harmless materials the productsof incomplete combustion that contaminate the exhaust gases of internalcombustion engines. In still another aspect, it relates to a process andapparatus for bringing more rapidly to its effective operatingtemperature the catalyst bed of a catalytic muffler system of aninternal combustion engine.

In the operation of an internal combustion engine such as the type usedon automobiles, the combustion process in the cylinders of the engineproduces from the hydrocarbon fuel some products of incompletecombustion. These products include, among others, carbon monoxide andunburned hydrocarbons. Unless further steps are taken these products areexhausted to the air where they contribute to air pollution.

Generally speaking, the generation of these materials is greatest when acold engine is started and is operated with the choke on. For a shortperiod of time after starting a cold engine, the hydrocarbon and carbonmonoxide emissions are several times greater than such emissions from ahot engine operating at the same speed and load. The high rate ofhydrocarbon and carbon monoxide emissions during the warm-up period is amajor problem in trying to meet federal emission standards establishedfor the 1975 vehicles.

The generation of these emissions-also tends to increase when the engineis not in good repair. Thus older automobiles and those not operating atpeak efficiency, i.e., out of tune are the worst offenders.

Amethod devised for ameliorating this problem involves directing theexhaust gases through a muffler which contains a bed of catalyst of atype that will oxidize the harmful carbon monoxide and hydrocarbons toan innocuous mixture of water and carbon dioxide. To be effective thecatalyst bed must be brought to a temperature at which the oxidation ofcarbon monoxide and unburned hydrocarbons will occur. Although thistemperature will vary depending upon the nature of the catalyst,generally at least about 600F. is required. Therefore, immediately afterstartup of the engine and for a period of time thereafter, until theexhaust gases gradually raise the catalyst bed to its effectivetemperature, the harmful components in the exhaust gases pass throughthe catalyst bed and are discharged unchanged to the atmosphere.

In view of the delay between engine startup and the time when thecatalyst bed reaches its operating temperature, it can be seen thatengine emissions and concomitantly air pollution can be reduced if amethod can be devised for more quickly raising the catalyst bed to asufficiently high temperature for it to operate effectively.

SUMMARY OF THE INVENTION An object of this invention is to reduce oreliminate harmful components found in the exhaust gases of internalcombustion engines.

Yet another object of this invention is to provide a process andapparatus for more rapidly bringing the catalyst bed of a catalyticmuffler to its effective operating temperature so as to minimize thedischarge to the atmosphere of unchanged contaminants in the exhaustgases of an internal combustion engine.

In accordance with this invention a process is provided which comprisescombining, just after startup, the exhaust gases from an internalcombustion engine with air and unburned fuel and igniting the mixture toform hot combustion gases. These gases are conducted, in direct heatexchange, through the cold catalyst bed of a catalytic muffler so as tomore rapidly raise its temperature to a level at which it can operateeffectively.

Further, in accordance with this invention, there is provided anapparatus for improving the operation of a catalytic muffler systemdesigned for removing harmful contaminants from the exhaust gases of aninternal combustion engine comprising a catalytic muffler having acatalyst-containing chamber and a combustion chamber in combination withmeans to provide a mixture of air, exhaust gases, and unburned fuel tothe combustion chamber wherein means are provided to ignite the mixtureand conduct the gases from the resulting combustion into thecatalyst-containing chamber. Additional means are provided to initiateand terminate the operation of the mixing and ignition means.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a cross section view of theapparatus of this invention.

FIG. 2 is a schematic of an electrical control circuit of thisinvention.

DESCRIPTION OF PREFERRED EMBODIMENTS Although this invention can beapplied to a wide variety of power systems using internal combustionengines, for the purposes of its illustration it will be described asbeing employed in conjunction with an engine used to power anautomobile. However, as will be appreciated by one skilled in the art,it need not be limitedthereto.

Referring to the drawing and specifically to FIG. 11, the numeral 10represents an internal combustion engine of the type used in aconventional automobile. Operation of the automobile generates exhaustgases which are transferred from the engine through manifold exhaustsystem ill. These exhaust gases are channeled through conduit 112 into acatalytic muffler M through inlet 13. Catalytic muffler I4 is any of aconventional type used to muffle the sound of the engine and to catalyzethe oxidative conversion of the undesirable products of incompletecombustion present in the exhaust gases to harmless substances. Thesecontaminants are comprised of carbon monoxide and unburned hydrocarbonsthat are oxidized to carbon dioxide and water during their passagethrough catalyst bed of catalyst-containing chamber 15. Typical catalystmaterials useful in these catalytic mufflers are the metals of groups I,V, VI, and VIII of the periodic table or the corresponding oxides.Suitable materials are metals such as vanadium, chromium, manganese,iron, cobalt, nickel, copper, molybdenum, palladium, platinum, titanium,tin, their oxides or mixtures thereof. To improve their effectiveness,the catalyst metals or metal oxides can be coated on or impregnated in asuitable support material. These support materials are usually selectedfrom inorganic refractory oxides such as silica, alumina, calcineddiatomaceous earth, kiselguhr and the like. The catalyst particles maybe of a variety of shapes including spherical, cylindrical and otherregular shapes as well as irregular shapes. Particle size may vary also.Generally a size and shape are selected to maximize contact of theexhaust gases with the catalyst surface without unduly impeding flowthrough the bed of material.

The muffler 14 is modified by including a combustion chamber 16 betweeninlet 13 and the remaining portion of muffler 14. The combustion chamberis in open communication with the rest of the muffler 14 throughcommunication means 17 which may be of any suitable type such as aconduit, foraminous screen or the like. After their passage through thecatalyst bed, exhaust gases are transmitted from muffler 14 to theatmosphere through exit port 18.

Conduit 12 is intersected prior to inlet 13 by auxiliary air supply line19 through which air can be directed from air blower 20 through checkvalve 21 into conduit 12 where it can mix with exhaust gases. Air blower20 may be of any suitable type but a centrifugal pump capable ofsupplying up to 100 cubic feet per minute is preferred. Check valve 21is disposed so as to be open during the operation of air blower 20 butotherwise to be closed in order that exhaust gases will not be able toescape by passing through the blower 20 when it is not in operation. Airblower 20 derives its power from the electrical system of the engine aswill be shown hereinafter.

Injection means 22 are provided to introduce unburned fuel as a spray tocombustion chamber 16. The unburned fuel for injection is taken fromfuel line 23 after passing through the fuel pump (not shown) by means offeeder line 24. A valve 25, preferably a solenoid valve, is provided tocontrol the flow of fuel to the injection means 22. The operation ofthis valve can be made automatic as will be described hereinafter. Theoperation of the fuel pump provides the required pressure for the spray.

A means 26 is provided for igniting a mixture of air, exhaust gases andunburned fuel in combustion chamber 16. Any means suitable for thispurpose may be employed but a spark or glow plug is preferred because ofthe ready availability of electrical power from the auto electric systemrepresented by battery 27.

Referring now to FIG. 2 which represents an electrical control systemthat may be used to this invention, battery 27 is represented as a 12volt storage battery of the type that is used in automobiles. In theoperation of this invention closing the ignition switch 28 (shown inopen position) will not only activate the main ignition system 29(designated on the drawing but not shown in detail) and start the enginebut will also energize coil 30. Coil 30 operates to close delay switch31 (shown in open position). After the preset delay period elapses,switch 31 closes, completing the circuit that provides power to airblower 20, opens solenoid valve 25 and energizes igniter circuit 32 forignition means 26. Additionally, coil 33 is energized which operates toopen delay switch 34 (shown in closed position). When the preset delayperiod for switch 34 has elapsed, it opens, thereby breaking the circuitthat operates the ignition circuit 32, solenoid valve 25 and air blower20. When the operation of the engine itself is terminated, switch 31returns to an open position while switch 34 returns to its closedposition in order that the cycle may be repeated when the engine isrestarted at a later time.

The circuit of FIG. 2 also serves the remainder of the automobileelectrical system, including lights, windshield wipers, power seat, andother accessories, although details are not shown on the drawing.

A delay switch suitable for use in this invention is Square D class 8501type GDO-l I-GE DC control relay with 12 volt operating coils andpneumatic timers adjustable from 0.2 second to 1 minute (accuracy i 15percent) which is commercially available from the Square D Company, ParkRidge, Ill.

In the actual practice of this invention, the purpose for setting delayswitch 31 to close after the closing of ignition switch 28 is to allowthe engine startup sequence to have at its disposal essentially all theelectrical power that battery 27 can deliver. As will be appreciated byone skilled in the art, the drawing off of electrical power from thebattery to operate auxiliary systems can hamper or defeat the enginestartup process. This problem is most severe during cold weather, whenthe battery is old or the engine difficult to start for reasons ofmechanical defect or a combination of these. The timer for this delayswitch may be set for any period of time sufficient to insure thatstartup will be satisfactory. However, in order to minimize the periodafter startup when the apparatus of the invention is not operating, adelay of about 2 seconds is preferred.

It is within the spirit of this invention to use any other suitablemeans that will automatically initiate and terminate the operation ofair blower 20, valve 25 and ignition means 26.

In the actual operation of this invention, startup of the engine 10results -in the generation of exhaust gases. These gases are led fromthe engine through exhaust manifold 11 and conduit 12. After a 2 seconddelay, as provided by the electrical circuitry of FIG. 2 and describedabove or other suitable means, air blower 20 begins to operate with thesimultaneous opening of check valve 21. The flow of air generated passesthrough auxiliary air supply line 19 and is combined in conduit 12 witha stream of exhaust gases. This mixture enters combustion chamber 16through inlet 13 where it is combined with a spray of unburned fuelsupplied from fuel line 23 through valve 25, feeder line 24 and sprayinjection means 22. The rate of unburned fuel delivery may vary butgenerally about (H to 1 cc of liquid fuel per second will be adequate.

The mixture of air, exhaust gases and unburned fuel is ignited byignition means 26. The resulting combustion generates high temperaturegases which pass through communication means 17 and into catalystcontaining chamber 15. The high temperature gases, by direct heatexchange, elevate the temperature of the initially cold catalyst bed inchamber 15 and after passage through it are exhausted from the muffler14 to the air through exit port 18.

The termination of the operation of the air blower 20 and ignition means26 and the closing of valve 25 to stop the flow of unburned fuel iscontrolled by the opening of delay switch 34 as shown in FIG. 2. Theopening of this switch is delayed for a period of time sufficient toallow the high temperature gases to elevate the temperature of theleading edge of the catalyst bed in chamber 15 to a level at which thecatalyzed oxidation of hydrocarbons and carbon monoxide will occur.Generally this will require a delay of from about 8 to 30 seconds afterthe initial closing of delay switch 311 initiates the operation of thecomponents just described. However, a delay of from about to 20 secondswill be sufficient for most catalytic mufflers, depending upon thenature of the catalyst bodies used, size and design of the muffler, etc.

Once the leading edge portion of the catalyst bed in chamber has beenraised to its effective operating temperature, catalytic oxidation ofexhaust components will add heat to the exhaust stream and assist inelevating the temperature of the remainder of the bed.

From the foregoing description it can be seen that by employing thisinvention the period of time during engine warmup when a catalyticmuffler is inoperative because of the low temperature of the catalystbed can be reduced.

I claim:

1. A process for rapidly bringing to its operating temperature thecatalyst bed of a catalytic muffler, said catalytic muffler beingdisposed so as to treat the exhaust gases from an internal combustionengine, comprising the steps:

a. initiating ignition of said internal combustion engine, said ignitionautomatically initiating a predetermined delay interval before b.automatically mixing the exhaust gases from said internal combustionengine with air and unburned fuel and igniting said mixture for apredetermined period,

c. conducting the gaseous combustion products resulting from saidignition and direct heat exchange with said catalyst bed, and

d. automatically terminating mixing the exhaust gases from said internalcombustion engine with air and unburned fuel and terminating ignitingsaid mixture at the end of said period.

2. The process according to claim 1 wherein the mixing of said exhaustgases with air and unburned fuel and subsequent ignition is conductedfor a period of from 8 to 30 seconds.

3. A process according to claim 1 wherein the air is combined with saidexhaust gases prior to the combination with the unburned fuel.

4. An apparatus for eliminating the products of incomplete combustion inthe exhaust stream of an internal combustion engine comprising:

a. a catalytic muffler for converting the products of incompletecombustion from said engine to harmless materials, having a combustionchamber and a catalyst containing chamber,

b. inlet means to said combustion chamber for introducing exhaust gasesfrom said engine,

c. means for compressing air and mixing said air with said exhaust gasesprior to said inlet means,

d. means for injecting unburned fuel into said combustion chamber as afine spray,

e. means for igniting a mixture of said unburned fuel,

air and exhaust gases,

f. communication means between said combustion chamber and said catalystcontaining chamber,

g. exit means for passing gaseous products from said catalyst containingchamber to the atmosphere,

h. means for initiating the operation of said air compressing means,said spray injecting means and said igniting means said initiatingbeginning automatically after a predetermined delay interval afterstartup of said engine, and

i. means for automatically terminating the operation of said aircompressing means, said spray injecting means and said igniting meansafter a predetermined interval of operation after startup of saidengine.

5. An apparatus according to claim 4 wherein said initiating andterminating means are delay switches, said compressing means is acentrifugal blower, said ina spark plug.

said ignition means is

1. A process for rapidly bringing to its operating temperature thecatalyst bed of a catalytic muffler, said catalytic muffler beingdisposed so as to treat the exhaust gases from an internal combustionengine, comprising the steps: a. initiating ignition of said internalcombustion engine, said ignition automatically initiating apredetermined delay interval before b. automatically mixing the exhaustgases from said internal combustion engine with air and unburned fueland igniting said mixture for a predetermined period, c. conducting thegaseous combustion products resulting from said ignition and direct heatexchange with said catalyst bed, and d. automatically terminating mixingthe exhaust gases from said internal combustion engine with air andunburned fuel and terminating igniting said mixture at the end of saidperiod.
 2. The process according to claim 1 wherein the mixing of saidexhaust gases with air and unburned fuel and subsequent ignition isconducted for a period of from 8 to 30 seconds.
 3. A process accordingto claim 1 wherein the air is combined with said exhaust gases prior tothe combination with the unburned fuel.
 4. An apparatus for eliminatingthe products of incomplete combustion in the exhaust stream of aninternal combustion engine comprising: a. a catalytic muffler forconverting the products of incomplete combustion from said engine toharmless materials, having a combustion chamber and a catalystcontaining chamber, b. inlet means to said combustion chamber forintroducing exhaust gases from said engine, c. means for compressing airand mixing said air with said exhaust gases prior to said inlet means,d. means for injecting unburned fuel into said combustion chamber as afine spray, e. means for igniting a mixture of said unburned fuel, airand exhaust gases, f. communication means between said combustionchamber and said catalyst containing chamber, g. exit means for passinggaseous products from said catalyst containing chamber to theatmosphere, h. means for initiating the operation of said aircompressing means, said spray injecting means and said igniting meanssaid initiating beginning automatically after a predetermined delayinterval after startup of said engine, and i. means for automaticallyterminating the operation of said air compressing means, said sprayinjecting means and said igniting means after a predetermined intervalof operation after startup of said engine.
 5. An apparatus according toclaim 4 wherein said initiating and terminating means are delayswitches, said compressing means is a centrifugal blower, said injectionmeans is controlled by a fuel metering valve and said ignition means isa spark plug.